Gardeners Can Play an Important Role in Reducing Global Warming

Changes in climate due to global warming will create enormous new challenges for gardeners, given the strong relationship between our garden plants and climate variables such as temperatures and rainfall

04-18-2007
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Patty Glick

RESTON, VA -- Trade-in the SUV, use florescent light bulbs, turn down your thermostat. These are just some of the things we're being told we can do to reduce our impact on global warming. But according to a new report from the National Wildlife Federation, "A Gardeners Guide to Global Warming," there are also many things you can do in the garden that will help combat this serious and potentially devastating environmental problem caused by our voracious appetite for fossil fuels. And the spring gardening season is the perfect time to get started.

"As gardeners, we are both guardians and stewards of our environment," says Patty Glick, author of the report and Global Warming Specialist for the National Wildlife Federation. "There are many simple and thoughtful ways we can manage our gardens that can make an enormous difference in reducing the impacts of global warming."

A report from international climate scientists released in February of 2007 projects that the Earth's average temperature will rise by 4-11 degrees before the end of this century if our dependency on fossil fuels continues unabated. Another report from this same prestigious group of scientists says that changes are happening faster than expected and the harmful effects of global warming on daily life are already apparent. (see chart below for projected changes in your region).

As any gardener knows, even just one degree difference between 32 and 33 degrees Fahrenheit over a period of time can make a huge difference in a garden. Scientists are now finding what many gardeners have already been noticing; earlier leaf out and bloom times, earlier emergence of butterflies and other insects, and arrival of new bird species at the backyard feeder.

Many of the "hardiness zone maps" that gardeners rely on to identify which plants to choose for their gardens are already being adjusted to account for the impacts of global warming. The Arbor Day Foundation recently shifted Illinois, Indiana, Ohio and part of Michigan from Zone 5 to a warmer Zone 6 along with other zone changes.

In many states, the climate change may be so intense that states may no longer have a favorable climate for their official state tree or state flower before this century is out. Imagine Virginia or North Carolina without the flowering dogwood; Louisiana without bald cypress and magnolia; Kansas without the sunflower; or Ohio without the Ohio buckeye (see table below for list of official state trees and flowers in jeopardy).

Changes in climate due to global warming will no doubt create some enormous new challenges for gardeners given the strong relationship between our garden plants and climate variables such as temperatures and rainfall. As numerous studies show, any potential benefits from a longer growing season will only be outmatched by a host of problems.

Heavier downpours and more intense storms will lead to extensive flooding in vulnerable areas. At the other extreme, severe drought conditions plaguing parts of the nation over the past few years lead to watering restrictions for our gardens. With global warming, lack of sufficient water for gardens will become even more of a problem. Droughts and heat waves also encourage some of the most damaging garden pests such as aphids, spider mites, locusts and whiteflies. Garden weeds such as dandelion and lambsquarters are expected to thrive with global warming.

While weeds and pests in the garden can be frustrating and time consuming to control, the invasive species encouraged by global warming can wreak absolute havoc in a garden as they gain more of a foothold. Scientists estimate that global warming will enable 48 percent of the invasive plants and animals in this country to move further north as temperatures rise.

While predictions for global warming are dire, they are not inevitable. With ninety-one million households engaged in lawn and garden activities in this country, gardeners are both guardians and stewards of our environment. The National Wildlife Federation's report demonstrates that gardeners can play a big part in the solution to global warming.

"The National Wildlife Federation report will help gardeners understand the predicted impacts of global climate change on plant species, and gives them practical tools to address this urgent problem," says Marian Hill, Conservation Chairman of the Garden Club of America, who wrote the Foreword to NWF's report.

While the following conservation practices aren't new to many gardeners, they are made ever more important now given the threat of global warming.

Reduce the threat of invasive species and incorporate a diversity of native plants into your landscape. Global warming will contribute to a dramatic expansion of invasive, non-native plants and animals, which are able to take advantage of weakened ecosystems and out-compete native species. Gardeners can play an important role in minimizing the threat of invasive species expansion by removing invasive plants from the garden and choosing an array of native alternatives.

Higher average temperatures and changes in precipitation patterns will enable some of the most problematic species, including kudzu, garlic mustard, purple loosestrife and Japanese honeysuckle, to move into new areas. In addition, global warming will contribute to more severe infestations and habitat damage from both native and exotic insect pests, including black vine weevil, gypsy moth, bagworm and mountain pine beetle.

Contact your local/state native plant society to find out what plants are native to your area or check out NWF's web site for a listing at www.nwf.org/backyard/food

Limit water consumption. In many parts of the country, more severe heat waves, droughts and declining snowpack due to global warming will cause a considerable reduction in available water resources. There are a number of ways to reduce water consumption in your garden, which will be particularly important when water resources become scarce. Actions that can help include mulching, installing rain barrels, watering only in the morning and evening to avoid mid-day evaporation and using drip irrigation.

Compost kitchen and garden waste. Composting kitchen and garden waste can significantly reduce your contribution to global warming pollution, especially methane, a highly potent greenhouse gas. It also provides an excellent source of nutrients for your garden, which reduces the need for chemical fertilizers that pollute water supplies and take a considerable amount of energy to produce.

Establish a "green roof" and plant trees around your house. Planting rooftop gardens and planting trees near your home can significantly shield your home from the elements, reducing energy use for air conditioning in the summer and heating in the winter. One study showed that shade trees can reduce energy use for air conditioning by up to seventy percent. Trees also absorb and store carbon dioxide (CO2), which is the gas primarily responsible for global warming. Over an average life-span for a tree, it can remove a ton of CO2 from the atmosphere.

Develop a rain garden. Gardeners can reduce water pollution associated with heavy downpours by developing rain gardens, which capture stormwater runoff and help prevent it from entering local lakes, streams and coastal waters.

Reduce the use of gasoline-powered yard tools. Another important change you can make is to avoid using gasoline-powered tools such as lawn mowers, weed eaters and leaf blowers. Instead, use electric-powered or, better yet, human-powered tools such as push mowers, hand clippers and rakes. If this seems daunting, you might consider replacing some of your lawn with low maintenance shrubs, bushes or a native wildflower patch.

Improve your energy efficiency. One of the best ways to reduce your contribution to global warming pollution is to use more energy-efficient products. In your backyard alone, there are a number of actions you can take, including replacing regular outdoor light bulbs with compact fluorescents, installing outdoor automatic light timers and purchasing solar-powered garden products. You can increase the availability of energy efficient garden products as well as native plants by encouraging local home and garden retailers to carry these items.

Contact your elected officials. Gardeners can voice their concerns about global warming to their local, state and federal government representatives urging them to implement strong action plans to combat global warming.These actions can include: placing mandatory limits on global warming pollution, raising fuel economy standards for cars and SUVs, investing in clean and efficient energy technologies, requiring utilities to generate a share of their electricity from renewable energy sources, developing programs to reel in suburban sprawl and expanding recycling programs.

The more global warming pollution we allow to build up in the atmosphere, the greater the risk that we will disrupt the natural systems on which humans and wildlife rely. Fortunately, solutions are readily at hand and gardeners can make a major contribution to implementing those solutions so that the beauty and utility of our gardens will endure for future generations.

According to Suzanne DeJohn with the National Gardening Association, who wrote the Afterword for the report, "Individual gardeners may think they can't make a real difference. But imagine if all--or even half--the estimated 91 million gardeners nationwide took steps to reduce their energy consumption. Each of us can do our part in our own landscape."

Related Resources

Supporting Document

As gardeners, we are both guardians and stewards of our environment, and it is important for us to realize that there are many simple and thoughtful ways that we can work with nature to solve the problem.

Supporting Document

A report from international climate scientists released in February of 2007 projects that the Earth’s average temperature will rise by 4-11 degrees before the end of this century if our dependency on fossil fuels continues unabated.